A strong need exists for a reusable, high-security, tamper-indicating seal for safeguarding valuable components or material. This may include, for example, nuclear fuel stored in special canisters that are closed and secured, where the canisters are then kept in a secured room. A seal is placed on the secured canister and/or on the door to the room by an authorized secuity agent. A seal is distinguished from a lock in that it can be easily defeated to provide unauthorized access to the secured material. The main function of a seal is to provide indication whether anyone has tampered with or otherwise has had access to the secured material once it had been secured by the seal.
U.S. Pat. No. 4,118,057 discloses such a security seal. The patented seal utilizes a cable that can be looped through a locking mechanism of the confinement that is to be secured, and a seal body which defines a pair of openings through which the opposite ends of the cable can then be fed. The seal further has a mechanism therein for mechanically engaging the cable so as to preclude the separation of the cable from the seal. As long as the looped cable remains intact and secured to the seal, the locking mechanism cannot be operated. Also located within the seal is a coding arrangement consisting of many balls of different colors, where a random grouping of the balls is segregated when the seal has been set in place and is visible such as through a window in the seal. The color-sequence code, although randomly generated, would be unique to that seal for that setting. The seal can be opened by means of a standard Allen wrench or even a screwdriver, but the code is destroyed each and every time the seal is opened. Having once been opened, the seal would have generated a new random code when it was subsequently reset. Consequently, were anyone to attempt to open and reset the seal undetected, the chances of the same code being generated would be as remote as the permutation of randomness provided by the seal and its code system.
However, the patented seal might be defeated by completely removing it and replacing it with a counterfeit. In other words, the genuineness of the seal itself can be put in doubt, where a substitute seal could be put in place of the original and a security agent may not be alerted that something of this nature has happened. Further, where a number of similar seals are in common use, it is possible to selectively destroy the various seals and restructure from these various component parts a single counterfeit seal that would appear to be genuine. Also, the seal could be opened without disturbing the code, such as by selective drilling through the seal to release the cable; and it might be somewhat difficult without this fact being of prime concern to detect this false entry. It is possible therefore to frustrate the intended purpose of the patented seal by any of several ways not related to the random code and its uniqueness.